Mammals have a form of internal heat production localised to their mitochondria, which they ramp up in the cold. This heat production is localised to a specialised tissue call brown adipose tissue, or simply brown fat. A corresponding mechanism has been almost entirely overlooked in birds, likely because they lack brown fat, and conventional white fat is still considered highly inactive. Therefore, the prevailing belief is that birds produce heat only by ‘shivering’ with large skeletal muscle groups (primarily chest and thigh muscles). However, new findings challenge the prevailing view by suggestion there is ‘heat of unknown origin’ . One possible explanation for this is that birds can make their white fat reserves “browner.” This
Can birds use their fat to produce heat?
Mammals have a form of internal heat production localised to their mitochondria, which they ramp up in the cold. This heat production is localised to a specialised tissue call brown adipose tissue, or simply brown fat. A corresponding mechanism has been almost entirely overlooked in birds, likely because they lack brown fat, and conventional white fat is still considered highly inactive. Therefore, the prevailing belief is that birds produce heat only by ‘shivering’ with large skeletal muscle groups (primarily chest and thigh muscles). However, new findings challenge the prevailing view by suggestion there is ‘heat of unknown origin’ . One possible explanation for this is that birds can make their white fat reserves “browner.” This occurs through a substantial increase in the volume of mitochondria and metabolically active mitochondria in adipose tissue. The resultant ‘beige’ fat could potentially function similarly to brown fat. While we know that white fat can be ‘browned’ in various studies on humans and other mammals, the situation in birds remains entirely unknown.
We are currently studying white fat browning at the cellular level, by measuring mitochondrial respiration and aerobic enzyme activity, in Japanese quail. This project takes it to the next level, addressing how any browning in cold-exposed birds affect heat production at the whole-animal level. You will learn state-of-the-art physiological methods such as measurement of metabolic rate and electromyography (EMG), as well as honing generic skills in experimental design and bird husbandry. The duration is 30 or 45 credits, and starting time is in March or April 2024.
For more information, contact: Andreas Nord, andreas.nord@biol.lu.se